Coatings including an antioxidant

ABSTRACT

A coating including an antioxidant or a combination of antioxidant and another bioactive agent on a medical device is described.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation-in-part application of U.S. application Ser. No. 11/189,216, filed on Jul. 25, 2005, the teachings of which are incorporated hereto by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to a method of providing an antioxidant to a coating on a medical device such as a drug-delivery stent.

2. Description of the Background

Blood vessel occlusions are commonly treated by mechanically enhancing blood flow in the affected vessels, such as by employing a stent. Stents are used not only for mechanical intervention but also as vehicles for providing biological therapy. To effect a controlled delivery of an active agent in stent medication, the stent can be coated with a biocompatible polymeric coating. The biocompatible polymeric coating can function either as a permeable layer or a carrier to allow a controlled delivery of the agent.

Although stents work well mechanically, the chronic issues of restenosis and, to a lesser extent, stent thrombosis remain. Pharmacological therapy in the form of a drug delivery stent appears to be a feasible means to tackle these issues. Subacute thrombosis and neointimal hyperplasia are considered to be the leading complications after stenting. Various factors are believed to be involved in the process. Methods for reducing thrombosis and restenosis have been previously proposed. However, those methods are less satisfactory for reducing thrombosis or restenosis associated with stenting.

The embodiments disclosed herein address the above described problems.

SUMMARY OF THE INVENTION

Provided herein is a coating that includes an antioxidant for a medical device. The coating includes a polymer matrix, an antioxidant, and optionally heparin or a bioactive agent. In some embodiments, the coating can include a biobeneficial material. The coating can be biodegradable or nondegradable. In some embodiments, the medical device can be a stent. In some embodiments, the stent, itself, can be a polymeric biodegradable, bioerodable or bioabsorbable stent, terms which are used interchangeably unless specifically indicated, which can include the bioactive agent embedded in the body of the stent or coating in the stent.

In some embodiments, the antioxidant can be embedded within the coating of the body of the medical device. In some embodiments, the antioxidant can be attached to the surface of the coating or surface of the medical device.

In some embodiments, a coating or device can include two ore more antioxidants, at least one of the antioxidant can be butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), Vitamin E, a super-oxide dismutase mimetic (SODm), or combinations thereof.

Some examples of the bioactive agent that can be included in the coating or medical device include, but are not limited to, paclitaxel, docetaxel, estradiol, nitric oxide donors, super oxide dismutases, super oxide dismutases mimics, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-amino-TEMPO), tacrolimus, dexamethasone, rapamycin, rapamycin derivatives, 40-O-(2-hydroxy)ethyl-rapamycin (everolimus), 40-O-(3-hydroxy)propyl-rapamycin, 40-O-[2-(2-hydroxy)ethoxy]ethyl-rapamycin, and 40-O-tetrazole-rapamycin, 40-epi-(N1-tetrazolyl)-rapamycin (ABT-578), pimecrolimus, imatinib mesylate, midostaurin, clobetasol, mometasone, CD-34 antibody, abciximab (REOPRO), progenitor cell capturing antibody, prohealing drugs, prodrugs thereof, co-drugs thereof, or a combination thereof.

The medical device having the features described herein can be used for treating, preventing, or ameliorating a medical condition such as atherosclerosis, thrombosis, restenosis, hemorrhage, vascular dissection or perforation, vascular aneurysm, vulnerable plaque, chronic total occlusion, claudication, anastomotic proliferation (for vein and artificial grafts), bile duct obstruction, ureter obstruction, tumor obstruction, or combinations of these.

DETAILED DESCRIPTION

Provided herein is a coating that includes an antioxidant for a medical device. The coating includes a polymer matrix, an antioxidant, and optionally heparin or a bioactive agent. In some embodiments, the coating can include a biobeneficial material. The coating can be biodegradable or nondegradable. In some embodiments, the medical device can be a stent. In some embodiments, the stent, itself, can be a polymeric biodegradable, bioerodable or bioabsorbable stent, terms which are used interchangeably unless specifically indicated, which can include the bioactive agent embedded in the body of the stent or coating in the stent.

In some embodiments, the antioxidant can be embedded within the coating of the body of the medical device. In some embodiments, the antioxidant can be attached to the surface of the coating or surface of the medical device.

In some embodiments, a coating or device can include two ore more antioxidants, at least one of the antioxidant can be BHT, BHA, Vitamin E, a SODm, or combinations thereof.

Some examples of the bioactive agent that can be included in the coating or medical device include, but are not limited to, paclitaxel, docetaxel, estradiol, nitric oxide donors, super oxide dismutases, super oxide dismutases mimics, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-amino-TEMPO), tacrolimus, dexamethasone, rapamycin, rapamycin derivatives, 40-O-(2-hydroxy)ethyl-rapamycin (everolimus), 40-O-(3-hydroxy)propyl-rapamycin, 40-O-[2-(2-hydroxy)ethoxy]ethyl-rapamycin, and 40-O-tetrazole-rapamycin, 40-epi-(N1-tetrazolyl)-rapamycin (ABT-578), pimecrolimus, imatinib mesylate, midostaurin, clobetasol, mometasone, CD-34 antibody, abciximab (REOPRO), progenitor cell capturing antibody, prohealing drugs, prodrugs thereof, co-drugs thereof, or a combination thereof.

The medical device having the features described herein can be used for treating, preventing, or ameliorating a medical condition such as atherosclerosis, thrombosis, restenosis, hemorrhage, vascular dissection or perforation, vascular aneurysm, vulnerable plaque, chronic total occlusion, claudication, anastomotic proliferation (for vein and artificial grafts), bile duct obstruction, ureter obstruction, tumor obstruction, or combinations of these.

Antioxidants

As used herein, the term “antioxidant” refers to a substance that is capable of inhibiting, preventing, reducing or ameliorating oxidative reactions on another substance (e.g., a polymer, a bioactive agent or a therapeutic substance) when the antioxidant is used in a system (e.g., coating) that includes such other substances. An example of such “antioxidant” is oxygen scavenger.

The antioxidant useful in the present invention can be any volatile or non-volatile antioxidant, which can be natural or synthetic. Natural antioxidant refers to an antioxidant derived from a natural source, with or without modification. Synthetic antioxidant refers to any antioxidant that is not a natural antioxidant. For example, ascorbic acid (Vitamin C) can be a natural antioxidant. BHT, BHA, or a SODm can be a synthetic antioxidant.

In some embodiments, the antioxidant includes, but is not limited to, BHT, BHA, ascorbic acid (Vitamin C), folic acid, b vitamins, beta carotene, flavonoids, SODm, polyphenol antioxidants such as apigenin or combinations thereof.

In some embodiments, the term “antioxidant” can specifically exclude an antioxidant described above. For example, the term “antioxidant” can specifically exclude BHT, BHA or a SODm. In some embodiments, the term “antioxidant” can specifically exclude Vitamin E. In some embodiments, the term “antioxidant” can specifically exclude a super-oxide dismutase mimetic (SODm). In still some embodiments, the antioxidant can specifically exclude one of folic acid, b vitamins, beta carotene, flavonoids, polyphenol antioxidants such as apigenin or combinations thereof.

Super-Oxide Dismutase Mimetic

In some embodiments, a coating or device can include a super-oxide dismutase (SOD) mimetic (SODm). In some embodiments, the SODm can be attached to the surface of a coating or device. The SODm can be attached to the surface of a coating or device via covalent bonding or non-covalent bonding. Non-covalent bonding can be, e.g., ionic interaction, hydrogen bonding, or an interpenetrating network (IPN).

As used herein, the term SODm refers to any super-oxide dismutase (SOD) mimetic. SOD can have important effects on vascular pathophysiology. For example, SOD1-deficient mice have been found to produce more superoxide than their wild-type controls and have decreased endothelium-dependent and -independent vasodilation. SOD1 overexpression in mice causes a decrease in VSMC proliferation in response to EGF but no change in the aortic hypertrophic response to Angiotensin II. A separate study with mice overexpressing SOD1 on the apoE^(−/−) background showed no significant effect on aortic atherosclerotic lesion area. Total SOD2 deficiency is lethal in mice, and although partial SOD2 deficiency has been shown to cause an increase in atherosclerotic lesion formation at arterial branch points, there was no effect on vasomotor responses to serotonin, PGF2α, or acetylcholine at baseline or after inhibition of SOD1 and SOD3 with diethyldithiocarbamate. The second most abundant SOD isoform in blood vessels is SOD3, which is predominantly produced by VSMCs, but because of its location in the interstitium between ECs and VSMCs, it is thought to be essential for endothelial-dependent vasodilation by protecting NO as it diffuses from the ECs to the VSMCs. These differences in the regulation of vascular tone or in the formation of atherosclerotic lesions indicate the potential importance of the subcellular localization of antioxidant systems in the modulation of local oxidant signaling.

Some examples of SODm include, but are not limited to, low molecular weight SOD synzymes having a Mn(II) coordinated in a macrocyclic pentamine ring (Ref: Riley D P, Weiss R H. JACS 1994; 116:387-388). In some embodiments, a coating or device can specifically exclude a SODm described above.

A SODm can be included in the coating or device or attached to the surface of a coating or device with or without a spacer. Attaching a SODm to the surface of a coating or device can be achieved by, for example, attaching the SODm to a polymer on the surface of the coating or the device via coupling of the reactive group in the SODm molecule to the polymer. In some embodiments, attaching a SODm to the polymer can be achieved by photo or thermally initiated radical coupling, which are well known in the art. In some embodiments, covalent attachment of a SODm to a polymer in the coating can be accomplished for example by reacting isocyanate group on the polymer chain with amino group on SODm (ref. Udipi, K, et al. J. biomaterial Mater. Res., 51, 549-560, 2000).

In some embodiments, attachment of a SODm to the polymer can be induced via photo activation. For example, photo-reactive chemical(s) (PRC) can extract hydrogen on the surface in the form of C—H or Si—H bonds, and covalently couple directly to the surface. If the PRC contains chemically reactive groups, a SODm, can be bound to the PRC. As a result, a SODm can be covalently grafted to the carbon surface.

Examples of photo-reactive chemicals are from the benzophenone family, i.e. benzophenone tetracarboxylic dianhydride, benzoylbenzoic acid, benzoyl benzoyl chloride, 4-benzoylbenzoic acid N-hydroxysuccinimide ester, benzoyl benzoyl amine, or from azide family, i.e. substituted phenyl azide and substituted acyl azide.

The hydrogen extraction can be initiated by UV exposure of the PRC entity. The linking reaction between PRC to the SODm will be dependent on the specific structure of the molecule but can be readily carried out by an ordinary artisan. For example, an amine functional group on SODm can react with an anhydride or acyl chloride of substituted benzophenone. The PRC can be coupled to the carbon surface first and then coupled with the SODm, or vice versa.

In some embodiments, a SODm can be attached to a polymer to form a SODm/polymer conjugate. The SODm/polymer conjugate can then be included in a formulation for forming a coating or a device. The SODm/polymer conjugate can have a covalent bond or non-covalent bond between the SODm and the polymer.

In some embodiments, antioxidants can be susceptible to oxidation or chemical changes under certain conditions. For example, BHT and BHA at an elevated temperature can compromise the molecular integrity of the antioxidant or cause an volatile antioxidant to evaporate. Therefore, the conditions in the coating process or device forming process can affect the content of the antioxidant to minimize the reduction of the level of antioxidant.

In some embodiments, the loss of antioxidant(s) in the coating or device forming process can be reduced by controlling the processing conditions. Such control of processing conditions can be, e.g., duration of the process, exclusion of air or oxygen using inert atmosphere or lowering the processing temperature. In some embodiments, the sterilization process can be conducted at a low temperature. A low temperature of sterilization refers to a temperature from about 25° C. to about 55° C., e.g., from about 30° C. to about 45° C. In some embodiments, the baking process can be conducted at a low temperature or in vacuum. A low temperature of baking refers to a temperature from about 25° C. to about 55° C. with and without vacumm. The procedure or process of coating or forming a medical device including stent is well documented in the art.

In some embodiments, the content of the antioxidant in a coating or device can be maintained or enhanced by adding an additional amount of the antioxidant (e.g., BHT or BHA) in the formulation forming the coating or device. Such additional amount depends from the chemical, physical or physiological nature of the antioxidant. For example, in the coating formulation, the BHT level can be increased up to about 60 wt %. Other types of antioxidant such as vitamin C can have a level from about 60 wt %. If a coating already contains an active agent, the antioxidant can be added as a second active agent in the coating at an amount that can be up to about 50 wt %. The active agent can be, e.g., paclitaxel, docetaxel, estradiol, nitric oxide donors, super oxide dismutases, super oxide dismutases mimics, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-amino-TEMPO), tacrolimus, dexamethasone, rapamycin, rapamycin derivatives, 40-O-(2-hydroxy)ethyl-rapamycin (everolimus), 40-O-(3-hydroxy)propyl-rapamycin, 40-O-[2-(2-hydroxy)ethoxy]ethyl-rapamycin, and 40-O-tetrazole-rapamycin, 40-epi-(N1-tetrazolyl)-rapamycin (ABT-578), pimecrolimus, imatinib mesylate, midostaurin, clobetasol, mometasone, CD-34 antibody, abciximab (REOPRO), progenitor-cell-capturing antibody, or combinations thereof.

Biocompatible Polymers

A coating or device having an antioxidant described herein can include one or more biocompatible polymer(s). The biocompatible polymer can be biodegradable (bioerodable or bioabsorbable) or nondegradable. Representative biocompatible polymers include, but are not limited to, poly(ester amide), polyhydroxyalkanoates (PHA), poly(3-hydroxyalkanoates) such as poly(3-hydroxypropanoate), poly(3-hydroxybutyrate), poly(3-hydroxyvalerate), poly(3-hydroxyhexanoate), poly(3-hydroxyheptanoate) and poly(3-hydroxyoctanoate), poly(4-hydroxyalkanaote) such as poly(4-hydroxybutyrate), poly(4-hydroxyvalerate), poly(4-hydroxyhexanote), poly(4-hydroxyheptanoate), poly(4-hydroxyoctanoate) and copolymers including any of the 3-hydroxyalkanoate or 4-hydroxyalkanoate monomers described herein or blends thereof, poly(D,L-lactide), poly(L-lactide), polyglycolide, poly(D,L-lactide-co-glycolide), poly(L-lactide-co-glycolide), polycaprolactone, poly(lactide-co-caprolactone), poly(glycolide-co-caprolactone), poly(dioxanone), poly(ortho esters), poly(anhydrides), poly(tyrosine carbonates) and derivatives thereof, poly(tyrosine ester) and derivatives thereof, poly(imino carbonates), poly(glycolic acid-co-trimethylene carbonate), polyphosphoester, polyphosphoester urethane, poly(amino acids), polycyanoacrylates, poly(trimethylene carbonate), poly(iminocarbonate), polyurethanes, polyphosphazenes, silicones, polyesters, polyolefins, polyisobutylene and ethylene-alphaolefin copolymers, acrylic polymers and copolymers, vinyl halide polymers and copolymers, such as polyvinyl chloride, polyvinyl ethers, such as polyvinyl methyl ether, polyvinylidene halides, such as polyvinylidene chloride, polyacrylonitrile, polyvinyl ketones, polyvinyl aromatics, such as polystyrene, polyvinyl esters, such as polyvinyl acetate, copolymers of vinyl monomers with each other and olefins, such as ethylene-methyl methacrylate copolymers, polycarbonates, polyoxymethylenes, polyimides, polyethers, poly(glyceryl sebacate), poly(propylene fumarate), poly(n-butyl methacrylate), poly(sec-butyl methacrylate), poly(isobutyl methacrylate), poly(tert-butyl methacrylate), poly(n-propyl methacrylate), poly(isopropyl methacrylate), poly(ethyl methacrylate), poly(methyl methacrylate), epoxy resins, polyurethanes, rayon, rayon-triacetate, cellulose acetate, cellulose butyrate, cellulose acetate butyrate, cellophane, cellulose nitrate, cellulose propionate, cellulose ethers, carboxymethyl cellulose, polyethers such as poly(ethylene glycol) (PEG), copoly(ether-esters) (e.g. PEO/PLA), polyalkylene oxides such as poly(ethylene oxide), poly(propylene oxide), poly(ether ester), polyalkylene oxalates, polyphosphazenes, phosphoryl choline, choline, poly(aspirin), polymers and co-polymers of hydroxyl bearing monomers such as HEMA, hydroxypropyl methacrylate (HPMA), hydroxypropylmethacrylamide, PEG acrylate (PEGA), PEG methacrylate, 2-methacryloyloxyethylphosphorylcholine (MPC) and n-vinyl pyrrolidone (VP), carboxylic acid bearing monomers such as methacrylic acid (MA), acrylic acid (AA), alkoxymethacrylate, alkoxyacrylate, and 3-trimethylsilylpropyl methacrylate (TMSPMA), poly(styrene-isoprene-styrene)-PEG (SIS-PEG), polystyrene-PEG, polyisobutylene-PEG, polycaprolactone-PEG (PCL-PEG), PLA-PEG, poly(methyl methacrylate)-PEG (PMMA-PEG), polydimethylsiloxane-co-PEG (PDMS-PEG), poly(vinylidene fluoride)-PEG (PVDF-PEG), PLURONIC™ surfactants (polypropylene oxide-co-polyethylene glycol), poly(tetramethylene glycol), hydroxy functional poly(vinyl pyrrolidone), biomolecules such as collagen, chitosan, alginate, fibrin, fibrinogen, cellulose, starch, collagen, dextran, dextrin, fragments and derivatives of hyaluronic acid, heparin, fragments and derivatives of heparin, glycosamino glycan (GAG), GAG derivatives, polysaccharide, elastin, chitosan, alginate, or combinations thereof. In some embodiments, the coating or device described herein can exclude any one of the aforementioned polymers.

As used herein, the terms poly(D,L-lactide), poly(L-lactide), poly(D,L-lactide-co-glycolide), and poly(L-lactide-co-glycolide) can be used interchangeably with the terms poly(D,L-lactic acid), poly(L-lactic acid), poly(D,L-lactic acid-co-glycolic acid), or poly(L-lactic acid-co-glycolic acid), respectively.

In some embodiments, the coating or device can include a fluoropolymer such as a Solef™ polymer (e.g., PVDF-HFP).

In some embodiments, the coating or device can further include a biobeneficial material. The biobeneficial material can be polymeric or non-polymeric. The biobeneficial material is preferably substantially non-toxic, non-antigenic and non-immunogenic. A biobeneficial material is one that enhances the biocompatibility of a device by being non-fouling, hemocompatible, actively non-thrombogenic, or anti-inflammatory, all without depending on the release of a pharmaceutically active agent.

Representative biobeneficial materials include, but are not limited to, polyethers such as poly(ethylene glycol), copoly(ether-esters) (e.g. PEO/PLA), polyalkylene oxides such as poly(ethylene oxide), poly(propylene oxide), poly(ether ester), polyalkylene oxalates, polyphosphazenes, phosphoryl choline, choline, poly(aspirin), polymers and co-polymers of hydroxyl bearing monomers such as hydroxyethyl methacrylate (HEMA), hydroxypropyl methacrylate (HPMA), hydroxypropylmethacrylamide, poly(ethylene glycol) acrylate (PEGA), PEG methacrylate, 2-methacryloyloxyethylphosphorylcholine (MPC) and n-vinyl pyrrolidone (VP), carboxylic acid bearing monomers such as methacrylic acid (MA), acrylic acid (AA), alkoxymethacrylate, alkoxyacrylate, and 3-trimethylsilylpropyl methacrylate (TMSPMA), poly(styrene-isoprene-styrene)-PEG (SIS-PEG), polystyrene-PEG, polyisobutylene-PEG, polycaprolactone-PEG (PCL-PEG), PLA-PEG, poly(methyl methacrylate)-PEG (PMMA-PEG), polydimethylsiloxane-co-PEG (PDMS-PEG), poly(vinylidene fluoride)-PEG (PVDF-PEG), PLURONIC™ surfactants (polypropylene oxide-co-polyethylene glycol), poly(tetramethylene glycol), hydroxy functional poly(vinyl pyrrolidone), biomolecules such as fibrin, fibrinogen, cellulose, starch, collagen, dextran, dextrin, hyaluronic acid, fragments and derivatives of hyaluronic acid, heparin, fragments and derivatives of heparin, glycosamino glycan (GAG), GAG derivatives, polysaccharide, elastin, chitosan, alginate, silicones, PolyActive™, and combinations thereof. In some embodiments, the coating or device can exclude any one of the aforementioned polymers.

The term PolyActive™ refers to a block copolymer having flexible poly(ethylene glycol) and poly(butylene terephthalate) blocks (PEGT/PBT). PolyActive™ is intended to include AB, ABA, BAB copolymers having such segments of PEG and PBT (e.g., poly(ethylene glycol)-block-poly(butyleneterephthalate)-block poly(ethylene glycol) (PEG-PBT-PEG).

In a preferred embodiment, the biobeneficial material can be a polyether such as poly(ethylene glycol) (PEG) or polyalkylene oxide.

Above listed polymers can be used as a drug carrier for active agents or topcoat to control the drug release. Alternatively, one active agent (such as antioxidant) can be imbedded in one biocompatible coating and another active agent (anti-proliferative agent) can be coated with the polymer on the top of the layer or vice versa.

Bioactive Agents

In some embodiments, the coating or device having the features described herein can include one or more bioactive agents. The bioactive agents can be any bioactive agent that is therapeutic, prophylactic, or diagnostic. These agents can have anti-proliferative or anti-inflammatory properties or can have other properties such as antineoplastic, antiplatelet, anti-coagulant, anti-fibrin, antithrombonic, antimitotic, antibiotic, antiallergic, and antioxidant properties. These agents can be cystostatic agents, agents that promote the healing of the endothelium such as NO releasing or generating agents, agents that attract endothelial progenitor cells, or agents that promote the attachment, migration and proliferation of endothelial cells (e.g., natriuretic peptide such as CNP, ANP or BNP peptide or an RGD or cRGD peptide), while quenching smooth muscle cell proliferation. Examples of suitable therapeutic and prophylactic agents include synthetic inorganic and organic compounds, proteins and peptides, polysaccharides and other sugars, lipids, and DNA and RNA nucleic acid sequences having therapeutic, prophylactic or diagnostic activities. Nucleic acid sequences include genes, antisense molecules that bind to complementary DNA to inhibit transcription, and ribozymes. Some other examples of other bioactive agents include antibodies, receptor ligands, enzymes, adhesion peptides, blood clotting factors, inhibitors or clot dissolving agents such as streptokinase and tissue plasminogen activator, antigens for immunization, hormones and growth factors, oligonucleotides such as antisense oligonucleotides and ribozymes and retroviral vectors for use in gene therapy. Examples of anti-proliferative agents include rapamycin and its functional or structural derivatives, 40-O-(2-hydroxy)ethyl-rapamycin (everolimus), and its functional or structural derivatives, paclitaxel and its functional and structural derivatives. Examples of rapamycin derivatives include methyl rapamycin (ABT-578), 40-O-(3-hydroxy)propyl-rapamycin, 40-O-[2-(2-hydroxy)ethoxy]ethyl-rapamycin, and 40-O-tetrazole-rapamycin. Examples of paclitaxel derivatives include docetaxel. Examples of antineoplastics or antimitotics include methotrexate, azathioprine, vincristine, vinblastine, fluorouracil, doxorubicin hydrochloride (e.g. Adriamycin® from Pharmacia & Upjohn, Peapack N.J.), and mitomycin (e.g. Mutamycin® from Bristol-Myers Squibb Co., Stamford, Conn.). Examples of such antiplatelets, anticoagulants, antifibrin, and antithrombins include sodium heparin, low molecular weight heparins, heparinoids, hirudin, argatroban, forskolin, vapiprost, prostacyclin and prostacyclin analogues, dextran, D-phe-pro-arg-chloromethylketone (synthetic antithrombin), dipyridamole, glycoprotein Ib/IIIa platelet membrane receptor antagonist antibody, recombinant hirudin, thrombin inhibitors such as Angiomax (Biogen, Inc., Cambridge, Mass.), calcium channel blockers (such as nifedipine), colchicine, fibroblast growth factor (FGF) antagonists, fish oil (omega 3-fatty acid), histamine antagonists, lovastatin (an inhibitor of HMG-CoA reductase, a cholesterol lowering drug, brand name Mevacor® from Merck & Co., Inc., Whitehouse Station, N.J.), monoclonal antibodies (such as those specific for Platelet-Derived Growth Factor (PDGF) receptors), nitroprusside, phosphodiesterase inhibitors, prostaglandin inhibitors, suramin, serotonin blockers, steroids, thioprotease inhibitors, triazolopyrimidine (a PDGF antagonist), nitric oxide or nitric oxide donors, super oxide dismutases, super oxide dismutase mimetic, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-amino-TEMPO), estradiol, anticancer agents, dietary supplements such as various vitamins, and a combination thereof. Examples of anti-inflammatory agents including steroidal and non-steroidal anti-inflammatory agents include tacrolimus, dexamethasone, clobetasol, combinations thereof. Examples of such cytostatic substance include angiopeptin, angiotensin converting enzyme inhibitors such as captopril (e.g. Capoten® and Capozide® from Bristol-Myers Squibb Co., Stamford, Conn.), cilazapril or lisinopril (e.g. Prinivil® and Prinzide® from Merck & Co., Inc., Whitehouse Station, N.J.). An example of an antiallergic agent is permirolast potassium. Other therapeutic substances or agents that may be appropriate include alpha-interferon, pimecrolimus, imatinib mesylate, midostaurin, bioactive RGD, and genetically engineered endothelial cells. The foregoing substances can also be used in the form of prodrugs or co-drugs thereof. The foregoing substances also include metabolites thereof or prodrugs of the metabolites. The foregoing substances are listed by way of example and are not meant to be limiting. Other active agents that are currently available or that may be developed in the future are equally applicable.

The dosage or concentration of the bioactive agent required to produce a favorable therapeutic effect should be less than the level at which the bioactive agent produces toxic effects and greater than the level at which non-therapeutic results are obtained. The dosage or concentration of the bioactive agent can depend upon factors such as the particular circumstances of the patient, the nature of the trauma, the nature of the therapy desired, the time over which the ingredient administered resides at the vascular site, and if other active agents are employed, the nature and type of the substance or combination of substances. Therapeutic effective dosages can be determined empirically, for example by infusing vessels from suitable animal model systems and using immunohistochemical, fluorescent or electron microscopy methods to detect the agent and its effects, or by conducting suitable in vitro studies. Standard pharmacological test procedures to determine dosages are understood by one of ordinary skill in the art.

Examples of Medical Device

As used herein, a medical device may be any suitable medical substrate that can be implanted in a human or veterinary patient. Examples of such medical devices include self-expandable stents, balloon-expandable stents, stent-grafts, grafts (e.g., aortic grafts), heart valve prostheses, cerebrospinal fluid shunts, pacemaker electrodes, catheters, and endocardial leads (e.g., FINELINE and ENDOTAK, available from Guidant Corporation, Santa Clara, Calif.), anastomotic devices and connectors, orthopedic implants such as screws, spinal implants, and electro-stimulatory devices. The underlying structure of the device can be of virtually any design. The device can be made of a metallic material or an alloy such as, but not limited to, cobalt chromium alloy (ELGILOY), stainless steel (316L), high nitrogen stainless steel, e.g., BIODUR 108, cobalt chrome alloy L-605, “MP35N,” “MP20N,” ELASTINITE (Nitinol), tantalum, nickel-titanium alloy, platinum-iridium alloy, gold, magnesium, or combinations thereof. “MP35N” and “MP20N” are trade names for alloys of cobalt, nickel, chromium and molybdenum available from Standard Press Steel Co., Jenkintown, Pa. “MP35N” consists of 35% cobalt, 35% nickel, 20% chromium, and 10% molybdenum. “MP20N” consists of 50% cobalt, 20% nickel, 20% chromium, and 10% molybdenum. Devices made from bioabsorbable (e.g., bioabsorbable stent) or biostable polymers could also be used with the embodiments of the present invention.

Method of Use

Preferably, the medical device is a stent. The stent described herein is useful for a variety of medical procedures, including, by way of example, treatment of obstructions caused by tumors in bile ducts, esophagus, trachea/bronchi and other biological passageways. A stent having the above-described coating is particularly useful for treating diseased regions of blood vessels caused by lipid deposition, monocyte or macrophage infiltration, or dysfunctional endothelium or a combination thereof, or occluded regions of blood vessels caused by abnormal or inappropriate migration and proliferation of smooth muscle cells, thrombosis, and restenosis. Stents may be placed in a wide array of blood vessels, both arteries and veins. Representative examples of sites include the iliac, renal, carotid and coronary arteries.

For implantation of a stent, an angiogram is first performed to determine the appropriate positioning for stent therapy. An angiogram is typically accomplished by injecting a radiopaque contrasting agent through a catheter inserted into an artery or vein as an x-ray is taken. A guidewire is then advanced through the lesion or proposed site of treatment. Over the guidewire is passed a delivery catheter that allows a stent in its collapsed configuration to be inserted into the passageway. The delivery catheter is inserted either percutaneously or by surgery into the femoral artery, radial artery, brachial artery, femoral vein, or brachial vein, and advanced into the appropriate blood vessel by steering the catheter through the vascular system under fluoroscopic guidance. A stent having the above-described coating may then be expanded at the desired area of treatment. A post-insertion angiogram may also be utilized to confirm appropriate positioning.

While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications can be made without departing from this invention in its broader aspects. Therefore, the appended claims are to encompass within their scope all such changes and modifications as fall within the true spirit and scope of this invention. 

1. A medical device comprising a coating, the coating comprising an antioxidant selected from natural antioxidants, synthetic antioxidants, or combinations thereof, wherein the synthetic antioxidant is not butylated hydroxytoluene (BHT) or butylated hydroxyanisole (BHA), and wherein the natural antioxidant is not Vitamin E.
 2. The medical device of claim 1, wherein the antioxidant is selected from ascorbic acid, folic acid and b vitamins, beta carotene, flavonoids, a super-oxide dismutase mimetic (SODm), polyphenol antioxidants, apigenin or combinations thereof.
 3. The medical device of claim 2, wherein the SODm is attached to the surface of the coating.
 4. The medical device of claim 3, wherein the SODm is attached to a polymer in the coating.
 5. The medical device of claim 1, wherein the coating further comprises a bioactive agent.
 6. The medical device of claim 1, wherein the coating further comprises heparin.
 7. The medical device of claim 5, wherein the bioactive agent is selected from the group consisting of paclitaxel, docetaxel, estradiol, nitric oxide donors, super oxide dismutases, super oxide dismutases mimics, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-amino-TEMPO), tacrolimus, dexamethasone, rapamycin, rapamycin derivatives, 40-O-(2-hydroxy)ethyl-rapamycin (everolimus), 40-O-(3-hydroxy)propyl-rapamycin, 40-O-[2-(2-hydroxy)ethoxy]ethyl-rapamycin, and 40-O-tetrazole-rapamycin, 40-epi-(N1-tetrazolyl)-rapamycin (ABT-578), pimecrolimus, imatinib mesylate, midostaurin, clobetasol, mometasone, CD-34 antibody, abciximab (REOPRO), progenitor cell capturing antibody, prohealing drugs, prodrugs thereof, co-drugs thereof, or a combination thereof.
 8. The medical device of claim 1, which is a stent.
 9. The medical device of claim 1, which is a bioabsorbable stent.
 10. The medical device of claim 1, wherein the SODm comprises a Mn(II) coordinated in a macrocyclic pentamine ring.
 11. A bioabsorbable medical device comprising an antioxidant selected from natural antioxidants, synthetic antioxidants, or combinations thereof, wherein the synthetic antioxidant is not butylated hydroxytoluene (BHT) or butylated hydroxyanisole (BHA), and wherein the natural antioxidant is not Vitamin E.
 12. The bioabsorbable medical device of claim 11, wherein the antioxidant is selected from ascorbic acid, folic acid and b vitamins, beta carotene, flavonoids, a super-oxide dismutase mimetic (SODm), polyphenol antioxidants, apigenin or combinations thereof.
 13. The bioabsorbable medical device of claim 11, wherein the SODm is attached to the surface of the bioabsorbable medical device.
 14. The bioabsorbable medical device of claim 11, wherein the bioabsorbable medical device further comprises a bioactive agent.
 15. The bioabsorbable medical device of claim 11, wherein the bioabsorbable medical device further comprises heparin.
 16. The medical device of claim 14, wherein the bioactive agent is selected from the group consisting of paclitaxel, docetaxel, estradiol, nitric oxide donors, super oxide dismutases, super oxide dismutases mimics, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-amino-TEMPO), tacrolimus, dexamethasone, rapamycin, rapamycin derivatives, 40-O-(2-hydroxy)ethyl-rapamycin (everolimus), 40-O-(3-hydroxy)propyl-rapamycin, 40-O-[2-(2-hydroxy)ethoxy]ethyl-rapamycin, and 40-O-tetrazole-rapamycin, 40-epi-(N1-tetrazolyl)-rapamycin (ABT-578), pimecrolimus, imatinib mesylate, midostaurin, clobetasol, mometasone, CD-34 antibody, abciximab (REOPRO), progenitor cell capturing antibody, prohealing drugs, prodrugs thereof, co-drugs thereof, or a combination thereof.
 17. The bioabsorbable medical device of claim 11, which is a stent.
 18. The bioabsorbable medical device of claim 11, wherein the SODm comprises a Mn(II) coordinated in a macrocyclic pentamine ring.
 19. A method comprising applying to a medical device a formulation comprising an antioxidant selected from natural antioxidants, synthetic antioxidants, or combinations thereof, and forming a coating of the formulation on the medical device, wherein the synthetic antioxidant is not butylated hydroxytoluene (BHT) or butylated hydroxyanisole (BHA), wherein the synthetic antioxidant is not butylated hydroxytoluene (BHT) or butylated hydroxyanisole (BHA), and wherein the natural antioxidant is not Vitamin E.
 20. The method of claim 19, wherein the antioxidant is selected from ascorbic acid, folic acid and B vitamins, beta carotene, flavonoids, a super-oxide dismutase mimetic (SODm), polyphenol antioxidants, apigenin or combinations thereof.
 21. The method of claim 20, wherein the SODm is attached to the surface of the coating.
 22. The method of claim 20, wherein the SODm is attached to a polymer in the coating.
 23. The method of claim 19, wherein the formulation further comprises a bioactive agent.
 24. The method of claim 19, wherein the formulation further comprises heparin.
 25. The method of claim 24, wherein the bioactive agent is selected from the group consisting of paclitaxel, docetaxel, estradiol, nitric oxide donors, super oxide dismutases, super oxide dismutases mimics, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-amino-TEMPO), tacrolimus, dexamethasone, rapamycin, rapamycin derivatives, 40-O-(2-hydroxy)ethyl-rapamycin (everolimus), 40-O-(3-hydroxy)propyl-rapamycin, 40-O-[2-(2-hydroxy)ethoxy]ethyl-rapamycin, and 40-O-tetrazole-rapamycin, 40-epi-(N1-tetrazolyl)-rapamycin (ABT-578), pimecrolimus, imatinib mesylate; midostaurin, clobetasol, mometasone, CD-34 antibody, abciximab (REOPRO), progenitor cell capturing antibody, prohealing drugs, prodrugs thereof, co-drugs thereof, or a combination thereof.
 26. The method of claim 19, wherein the medical device is a stent.
 27. The method of claim 19, wherein the medical device is a bioabsorbable stent.
 27. The method of claim 19, wherein forming the coating comprises baking the coating, and sterilizing the coating.
 28. The method of claim 27, wherein the baking or sterilizing are conducted at a temperature between about 25° C. and about 55° C.
 29. The method of claim 20, wherein the SODm comprises a Mn(II) coordinated in a macrocyclic pentamine ring.
 30. A method comprising implanting the medical device of claim 1 into a human being in need of treatment for atherosclerosis, thrombosis, restenosis, hemorrhage, vascular dissection or perforation, vascular aneurysm, vulnerable plaque, chronic total occlusion, claudication, anastomotic proliferation (for vein and artificial grafts), bile duct obstruction, ureter obstruction, tumor obstruction, or combinations of these.
 31. A method, comprising implanting the medical device of claim 7 to the human being, into a human being in need of treatment for atherosclerosis, thrombosis, restenosis, hemorrhage, vascular dissection or perforation, vascular aneurysm, vulnerable plaque, chronic total occlusion, claudication, anastomotic proliferation (for vein and artificial grafts), bile duct obstruction, ureter obstruction, tumor obstruction, or combinations of these.
 32. A method comprising implanting the medical device of claim 8 into a human being in need of treatment for atherosclerosis, thrombosis, restenosis, hemorrhage, vascular dissection or perforation, vascular aneurysm, vulnerable plaque, chronic total occlusion, claudication, anastomotic proliferation (for vein and artificial grafts), bile duct obstruction, ureter obstruction, tumor obstruction, or combinations of these.
 33. A medical device comprising a coating, the coating comprising at least two antioxidants, wherein one antioxidant is selected from BHT, BHA, Vitamin E, a SODm or a combination thereof.
 34. The medical device of claim 33, wherein the other antioxidant is selected from ascorbic acid, folic acid and b vitamins, beta carotene, flavonoids, polyphenol antioxidants, apigenin or combinations thereof.
 35. The medical device of claim 33, wherein the SODm is attached to the surface of the coating.
 36. The medical device of claim 35, wherein the SODm is attached to a polymer in the coating.
 37. The medical device of claim 33, wherein the coating further comprises a bioactive agent.
 38. The medical device of claim 33, wherein the coating further comprises heparin.
 39. The medical device of claim 37, wherein the bioactive agent is selected from the group consisting of paclitaxel, docetaxel, estradiol, nitric oxide donors, super oxide dismutases, super oxide dismutases mimics, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-amino-TEMPO), tacrolimus, dexamethasone, rapamycin, rapamycin derivatives, 40-O-(2-hydroxy)ethyl-rapamycin (everolimus), 40-O-(3-hydroxy)propyl-rapamycin, 40-O-[2-(2-hydroxy)ethoxy]ethyl-rapamycin, and 40-O-tetrazole-rapamycin, 40-epi-(N1-tetrazolyl)-rapamycin (ABT-578), pimecrolimus, imatinib mesylate, midostaurin, clobetasol, mometasone, CD-34 antibody, abciximab (REOPRO), progenitor cell capturing antibody, prohealing drugs, prodrugs thereof, co-drugs thereof, or a combination thereof.
 40. The medical device of claim 33, which is a stent.
 41. The medical device of claim 33, which is a bioabsorbable stent.
 42. The medical device of claim 33, wherein the SODm comprises a Mn(II) coordinated in a macrocyclic pentamine ring.
 43. A bioabsorbable medical device comprising at least two antioxidants, wherein one antioxidant is selected from BHT, BHA, Vitamin E, a SODm or a combination thereof.
 44. The bioabsorbable medical device of claim 43, wherein the antioxidant is selected from ascorbic acid, folic acid and b vitamins, beta carotene, flavonoids, a super-oxide dismutase mimetic (SODm), polyphenol antioxidants, apigenin or combinations thereof.
 45. The bioabsorbable medical device of claim 43, wherein the SODm is attached to the surface of the bioabsorbable medical device.
 46. The bioabsorbable medical device of claim 43, wherein the bioabsorbable medical device further comprises a bioactive agent.
 47. The bioabsorbable medical device of claim 43, wherein the bioabsorbable medical device further comprises heparin.
 48. The medical device of claim 46, wherein the bioactive agent is selected from the group consisting of paclitaxel, docetaxel, estradiol, nitric oxide donors, super oxide dismutases, super oxide dismutases mimics, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-amino-TEMPO), tacrolimus, dexamethasone, rapamycin, rapamycin derivatives, 40-O-(2-hydroxy)ethyl-rapamycin (everolimus), 40-O-(3-hydroxy)propyl-rapamycin, 40-O-[2-(2-hydroxy)ethoxy]ethyl-rapamycin, and 40-O-tetrazole-rapamycin, 40-epi-(N1-tetrazolyl)-rapamycin (ABT-578), pimecrolimus, imatinib mesylate, midostaurin, clobetasol, mometasone, CD-34 antibody, abciximab (REOPRO), progenitor cell capturing antibody, prohealing drugs, prodrugs thereof, co-drugs thereof, or a combination thereof.
 49. The bioabsorbable medical device of claim 43, which is a stent.
 50. The bioabsorbable medical device of claim 43, wherein the SODm comprises a Mn(II) coordinated in a macrocyclic pentamine ring. 